Apparatus and methods for removal of combustibles, such as hydrocarbons from materials are known and have a variety of uses. For example, drilling fluids are used to remove drill cuttings during rotary drilling of various subterranean wells, such as oil wells. These drilling fluids are oil based. Solids control equipment is used on the surface to remove the cuttings from the drilling fluid returned to the surface with the cuttings. The drill cuttings become impregnated with the oil based drilling fluids. Disposal of oil impregnated cuttings is a problem because of strict pollution regulations and laws.
One solution for disposal of oil impregnated drill cuttings is to submit the drill cuttings to combustion under controlled conditions. See Lewis U.S. Pat. No. 3,570,420. Another, more recent solution is to heat the drill cuttings under controlled conditions to separate the combustible products, such as gaseous hydrocarbons, from the solid drill cuttings. See Schellstede U.S. Pat. No. 4,313,785, Morris U.S. Pat. No. 4,304,609 and Sample U.S. Pat. No. 4,139,462. However, each of these more recent designs utilizes an auger rotating within a heated tube. The auger type of design, however, involves several problems, including one or more of the following: limited pumping pressure, seal failures on the auger bearings, alignment problems between the auger and the heated tube causing galling of the inner surface of the heated tube, and retarded flow or plugging of drill cuttings between the auger and the heated tube.